The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A wireless local area network (WLAN) typically permits wireless communication between multiple network devices. A WLAN can be operated in a number of different modes including, for example, an “infrastructure mode” or an “ad hoc mode”. In a wireless network that operates according to the infrastructure mode (referred to herein as an “infrastructure mode network”), all network devices communicate with a central base station (e.g., an access point). In a wireless network that operates according to the ad hoc mode (referred to herein as a peer-to-peer (P2P) network), network devices communicate directly with each other rather than through a central base station.
Infrastructure mode networks typically include a discovery server and/or a coordination server for discovery and connection setup between network devices (e.g., mobile devices). The discovery and coordination servers obtain information regarding network connected peers and application-specific information. The discovery and coordination servers are typically located at an access point. A peer-to-peer (P2P) network generally does not include a discovery server, a coordination server, or an access point. Network devices (or peer devices) of a P2P network communicate directly with each other (referred to as WiFi direct).
Discovery of peer devices within a P2P network may include an active phase or find phase. An active phase may include a first network device transmitting probe messages to peer devices (i.e., other network devices). The first network device may transmit probe messages to join a P2P network and/or to communicate with another network device. A probe message includes, for example, a basic service set identifier (BSSID) and data rates of the first network device. Peer devices operating in a “listen” mode (at the time a probe message is sent by the first network device) may respond to the probe message by sending a probe response signal. The find phase may include toggling between listen and search modes.
Network devices typically operate in a “sleep” mode to conserve power. While operating in a sleep mode a network device may be partially powered down or fully powered down. Network devices that perform active and/or passive scanning may transition between operating in a listen mode and a sleep mode.